Revert "fixed max possible upload size for files app in admin screen"

This reverts commit 7f2208b9a11f608e7d726bf426fe4c2a672e058a.

Conflicts:
	apps/files/admin.php
only show the max possible upload of 2GB on a 32 bit system.
for a 64 bit system we have no such limitation
refs #856

Conflicts:
	apps/files/templates/admin.php
Merge pull request #1041 from owncloud/fixing-856-master

Fixing #856 master